Periodontitis is the leading cause of tooth loss in adults. A major limitation in the clinical management of patients susceptible to periodontal disease is the inability to detect active alveolar bone loss. Currently, the clinician diagnoses periodontitis based upon historical measures such as radiographs and probing pocket depths. The major shortcoming of using these measures is that they do not predict future disease activity. Recent advances in the diagnosis of metabolic skeletal disorders have lead to the investigation of biomarkers of periodontal alveolar bone loss. A class of bone collagen degradative by-products termed pyridinoline crosslinks (Pyds) are promising indicators of active bone resorption. We have demonstrated that Pyds have great potential as diagnostic aids for periodontal and pen-implant bone loss. To date, there is no simple method to detect Pyds in patients with periodontitis. In our research plan we propose the development of a test that can provide a "real-time" assessment of periodontal disease activity. Our Specific Aims in this Phase I application are: 1) to develop a rapid "chairside" immunoassay for the detection of Pyds (both deoxypyridinoline (Dpd) and C-telopeptide pyridinoline crosslink of Type I Collagen (ICTP)); and 2) to determine the ability of the chairside diagnostic test to discriminate between periodontal health and periodontitis cross-sectionally. This Phase I investigation if successful would lead to a Phase II application that would apply this rapid test to determine the diagnostic ability of Pyds to predict oral bone loss in a multicenter longitudinal study of patients susceptible to periodontal disease.